(1) Field of the Invention
This invention relates to substrate treating apparatus for treating, e.g. cleaning, substrates such as semiconductor wafers or glass substrates for liquid crystal displays (hereinafter called simply substrates) with a treating liquid.
(2) Description of the Related Art
Conventionally, this type of apparatus includes, for example, a treating tank for storing a treating liquid and receiving substrates, and a nozzle for supplying isopropyl alcohol (IPA) gas to a space above the treating tank (see Japanese Unexamined Patent Publication H10-22257, for example). With this apparatus, after supplying deionized water to the treating tank and cleaning substrates, IPA gas is supplied to the space above the treating tank to form an IPA atmosphere therein. By pulling up and moving the substrates in the IPA atmosphere, the deionized water adhering to the substrates is replaced with IPA to promote drying of the substrates.
The conventional apparatus with such construction has the following drawback.
The conventional apparatus can promote drying of the substrates to some degree by pulling up the substrates cleaned with deionized water out of the deionized water, and moving the substrates in the IPA atmosphere. However, deionized water adhering to fine patterns formed on the substrates cannot be dried sufficiently, and thus a possibility of unsatisfactory drying performance.
In the latest semiconductor devices in the field of memory, capacitors constructed in a cylindrical shape have begun to be employed as a technique for drastically increasing the degree of integration. Such a cylindrical structure has a very high aspect ratio, and it is particularly difficult to dry sufficiently deionized water having entered gaps of that structure. Thus, the above drawback is notable here. A similar problem can occur also with devices related to what is known as MEMS (Micro Electro Mechanical Systems).
It is conceivable to pull up substrates after replacing deionized water with a solvent before pulling up the substrates, instead of using deionized water as final treating liquid. In this case, however, although it is important to replace the deionized water with the solvent sufficiently, the concentration of deionized water in the solvent cannot be reduced below a certain level even if a large quantity of solvent is mixed into the deionized water. The solvent cannot replace the deionized water sufficiently. Thus, there still is a possibility of unsatisfactory drying performance due to the deionized water.
When pulling up the substrates after replacing the deionized water with the solvent as noted above, even if a large quantity of solvent is mixed into the deionized water, the deionized water having entered fine structures of the substrates gradually mixes into the treating liquid, resulting in a phenomenon of the deionized water concentration gradually increasing in the treating liquid. Thus, there still is a possibility of unsatisfactory drying performance due to the deionized water. In addition, when the substrates are pulled up, the fine structures could collapse due to the surface tension of the deionized water.
A conventional apparatus of this type may include a plurality of treating tanks, and a transport mechanism for transporting substrates from one treating tank to another. The apparatus successively treats the substrates in different treating tanks with different treating liquids or solutions (see Japanese Unexamined Patent Publication H10-22257, for example). Such apparatus performs a series of treatments while moving the substrates successively such that, for example, the substrates have surfaces lightly etched with BHF (buffered hydrofluoric acid) in the first treating tank, and cleaned with deionized water in the second treating tank. The deionized water is replaced with IPA (isopropyl alcohol) in the third treating tank, and the substrates are dried in a solvent vapor atmosphere in the fourth treating tank.
The conventional apparatus with such construction has the following drawback.
With the substrates having fine patterns formed thereon, the fine patterns could collapse when the substrates are moved from one treating tank to another, due to the surface tension of deionized water remaining in the patterns.